DDP3300A Datasheet, PDF (13/53 Pages) Micronas – Single-Chip Display and Deflection Processor

PRELIMINARY DATA SHEET
DDP 3300 A
2.2. Analog Back End
The digital RGB signals are converted to analog RGBs
using three video digital to analog converters (DAC) with
10-bit resolution. An analog brightness value is provided
by three additional DACs. The adjustment range is 40%
of the full RGB range.
The back-end allows insertion of an external analog
RGB signal. The RGB signal is key-clamped and in-
serted into the main RGB by the fast blank switch. The
external RGB signals are virtually handled as priority
bus signals. Thus, they can be overlaid or underlaid to
the digital picture. The external RGB signals can be ad-
justed independently as regards DC-level (brightness)
and magnitude (contrast).
Controlling the whitedrive/analog brightness and also
the external contrast and brightness adjustments is
done via the Fast Processor, located in the VPC 3200 A
(ref 2.3.5.). Control of the cutoff DACs is via I²C-bus reg-
isters.
Finally cutoff and blanking values are added to the RGB
signals. Cutoff (dark current) is provided by three 9-bit
DACs. The adjustment range is 60% of full scale RGB
range.
The analog RGB-outputs are current outputs with cur-
rent-sink characteristics. The maximum current drawn
by the output stage is obtained with peak white RGB.
2.2.1. CRT Measurement and Control
The display processor is equipped with an 8-bit PDM-
ADC for all measuring purposes. The ADC is connected
to the sense input pin, the input range is 0 to 1.5V. The
bandwidth of the PDM filter can be selected; it is
40/80 kHz for small/large bandwidth setting. The input
impedance is more than 1 MΩ.
Cutoff and white drive current measurement are carried
out during the vertical blanking interval. They always use
the small bandwidth setting. The current range for the
cutoff measurement is set by connecting a sense resis-
tor to the MADC input. For the whitedrive measurement,
the range is set by using another sense resistor and the
range select switch 2 output pin (RSW2). During the ac-
tive picture, the minimum and maximum beam current
is measured. The measurement range can be set by us-
ing the range select switch 1 pin (RSW1) as shown in
Fig. 2–10 and Fig. 2–11. The timing window of this mea-
surement is programmable. The intention is to automati-
cally detect letterbox transmission or to measure the ac-
tual beam current. All control loops are closed via the
external control microprocessor.
beam current
A
D
MADC
SENSE
RSW1 ^R2
RSW2 ^R3
R1
Fig. 2–10: MADC Range Switches
black
ultra black
Remark:
The adjustment for
IBRM, WDR, WDG,
WDB is done in the
VPC 3200 A
CR + IBRM + WDRV·WDR
CR + IBRM
cutoff
R
white
drive
R
CG + IBRM
cutoff
G
CB + IBRM
cutoff
B
active measure-
ment resistor
R1kR2kR3
RSW1=on, RSW2=on
PICTURE MEAS.
Lines
PMSO
Fig. 2–11: MADC Measurement Timing
R1
R1kR3
RSW2
=on
TUBE MEASUREMENT
TML
MICRONAS INTERMETALL
R
G
B
R1kR2kR3
RSW1=on, RSW2=on
PICTURE MEAS.
PMST
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